Was it on that morning you left for Beijing he discovered our secret?
A. that; where
B. which; that
C. when; that
D. that; when
网友回答
A. that; where
B. which; that
(答案→)C. when; that
D. that; when
解析：本题考查强调句型和定语从句。When you left for Beijing是定语从句修饰前面的that morning; you是 句子的主语，谓语动词：left for;宾语：Beijing.句子是完整的，应该选择关系副词。第二空的that与it was 是强调句型的基本结构。